The engine pressure ratio (EPR) is the total pressure ratio across a
jet engine
A jet engine is a type of reaction engine discharging a fast-moving jet of heated gas (usually air) that generates thrust by jet propulsion. While this broad definition can include rocket, Pump-jet, water jet, and hybrid propulsion, the term ...
, measured as the ratio of the total pressure at the exit of the propelling nozzle divided by the total pressure at the entry to the compressor.
Jet engines use either EPR or compressor/fan RPM as an indicator of thrust.
[ ] When EPR is used, the pressures are measured in front of the compressor and behind the turbine.
Integrated engine pressure ratio
The integrated engine pressure ratio (IEPR) is the ratio of the pressure at the core engine exhaust ''and'' fan discharge pressure compared to the intake pressure to the
gas turbine engine
A gas turbine, also called a combustion turbine, is a type of continuous flow internal combustion engine. The main parts common to all gas turbine engines form the power-producing part (known as the gas generator or core) and are, in the directi ...
. The IEPR is an engine indicator system unique to the
Rolls-Royce RB211
The Rolls-Royce RB211 is a British family of high-bypass turbofan engines made by Rolls-Royce. The engines are capable of generating of thrust. The RB211 engine was the first production three-spool engine, and turned Rolls-Royce from a signif ...
.
See also
*
Jet engine performance
The behavior of a jet engine and its effect both on the aircraft and the environment is categorized into different engineering areas or disciplines. The understanding of how a particular fuel flow produces a definite amount of thrust at a partic ...
*
Turbofan
The turbofan or fanjet is a type of airbreathing jet engine that is widely used in aircraft engine, aircraft propulsion. The word "turbofan" is a portmanteau of "turbine" and "fan": the ''turbo'' portion refers to a gas turbine engine which ac ...
References
* The Boeing Company '' Engine thrust control system '
US Patent 4248042Includes
Boeing
The Boeing Company () is an American multinational corporation that designs, manufactures, and sells airplanes, rotorcraft, rockets, satellites, telecommunications equipment, and missiles worldwide. The company also provides leasing and product ...
's discussion on EPR or IEPR being a better indicator of thrust.
External links
Pressure Variation EPR - NASA Animation
Engineering ratios
Aircraft engines
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